Coil for electrical apparatus.



H. B. SMITH. COIL FOR ELECTRICAL APPARATUS. APPLICATION FILED JAN.26,1910.

2 SHEETS-SHEET 1.

1,082,563. Patented Dec. 30, 1913.

IN NTOR H. B. SMITH. con. FOR ELECTRICAL APPARATUS. APPLICATION IILBD JAN. 26,1910.

INVENTOB 6.

AT.TORNEY B. on F Hm J. 1/ u m TL n .19 m m w m. 3 Q w d w W U N s IT ED STATES- OFFICE. Hanan) B. SMITH, or woncnsrnn, massncnnsnrrs, nssmnon. '10 wns'rmc'nousn nnncrnrc an]: mmnrnorunme COMPANY, a conronarron or rnmvsxnvmn.

Specification of Letters Patent.

Application flledlanuary 26, 1910. Serial 110,540,209.

COIL FOR ELECTRICAL. AIEl-"ARA'JFU'S.

Patented Dec. 30, 1913.

To all whom it may concern 1 Be it known that I, HAROLD B. SMITH, a

new and useful Improvement in Coils for Electrical Apparatus, of which the following is a specification.

My invention relates to coils for electrical apparatus and it has for its ob ect to rovide a .simple coil of spiral form;wh1 ch s all be especially adapted for use 1n high-voltage transformers and other similar apparatus and a particularly advantageous method of producing the same. y

In the construction of very hlgh-voltage vtransformers, it is often desirable to employ coils which are spiral in form and each-of which contains a single layer of turns 1n order that the coils may readily be insulated from each other and be cooled by contact with the oil or otherinsulating fluid in which they are immersed. It has heretofore been very difiicult to produce a coil of this kind if made of ordinary cotton-covered round wire conductors of small gage. There are, however, many advantages in uslng conductors of this kind, since they are cheaper than conductors of square or rectangular section and present a greater radiating surface to the insulating fluid in which they are disposed.

According to my present inventlon, I provide a coil which comprises a single layer of spirally wound convolutions which are stitched together by a zigzag sewing machine, the stitches alone being depended upon for holding the turns together in the completed coil.

1 It is evident that coils produced in accordance with my invention may be utilized for various purposes and that they may be formed of conductors of different gages having coverings of cotton, silk or other insulating fabric.

Figure 1 of the accompanying drawings is a perspective View of apparatus suitable for producing the coil which is illustrated in Fig. 2. Figs. 3 and 4 are, respectively, a plan View and an elevation of a guide roll which forms a part of the apparatus of Fig. 1. Fig. 5 is a plan view and Fig. 6 is a partial elevation, on a larger scale, of the mechanism shown in Fig. 1.

Referring to the drawings, the apparatus here shown comprises a table 1 which may be replaced by any suitable base a sewing .machine 2, which is adapted for zigzag center stitching, guide members 3 and 4, a p%ate 5 and a guide rod 6 for the center p ate.

The guide member 3 is shown in detail in Figs. 3 and 4 and comprises an under; late '7, which substantially corresponds,-in t ickness, to the diameter of the conducting wire of which the coil is to be wound, an overas shown at 13 in Fig. 3, to avoid interfering with the sewing machine needle and foot when the guide member is assembled on the table 1, as shown in Figs. 1 and 5. The roller 11- is provided with axial extensions 14 which project into slots 15 in the posts 9 and 10 in which helical springs 16 aredisposed. The springs produce a downward pressure on the extensions 14; of the rolls and their tension may be adjusted by screws 17, which are screw-threaded through caps 18 of the posts. The roller rests upon the coil which is in process of formation and keeps the convolutions flat against the surface of the table just as they are fed to the sewing machine. The post 10 is adjustably mounted on the plate 8 between two stationary blocks 17 and 18, which are screwed to the plate. The adjusting screw 19 is rotatably supported in the blocks 17 and 18" and is screwthreaded through the post 10, so that an adjustment of the post is produced by turning the screw.

The guide member 4. is intended to straighten the conductor as it is formed into the coil and also to guide the convolutions which are already wound. This device comprises a rod or shaft 19, which is supported in bearing blocks 20 and is provided with a frusto-conical projection 21 which extends over the outer edge of the coil near the guide member 3, on the side from which the conducting wire is fed. The bearing blocks 20 are preferably secured to a plate 22 which may be mounted on the table in any suitable position. The shaft may be adjusted longi tudinally, in order to vary the position of the frusto-conical projection 21, by means of a screw 23 which is rotatably supported b the bearing blocks directly above the sha t plate 8. The center plate'5 is provided with a screw-threaded projection 27 which extends upwardly, from its central point, through the slot 25. The nut 28 is screwed upon t e rojection 27, which extends upwardly from its central point through the slot 25. The nut 28 is screwed upon the projection 27 the arrangement of parts being such that the strip 6 serves as a guide for the center plate 5, which is adjustably mounted on the table 1.

-A pulley 29 is pivotally supported upon the under side otthe inner end of therod 26, and a cord or chain 30, which is attached to the projection'27 at-its inner end, passesover the pulley 29 and over the guide pulley 31, a weight 32 bein attached to its outer end. A second weig t 33 is attached to a cord 34 which passes over another pulley 35, located at the opposite side of the table,

the inner-end of thls cord being attached also tothe projection 27 The outer end of the rod 6 is screwed to the projection 36 or is otherwise to secure a stationary support.

The method of roducing coils by the mechanism above escribed is as follows: A disk or templet 37,'which corresponds, in thickness, to the diameter of the conductor, is concentrically attached to the center plate 5 and rests upon the table 1. The diameter of the templet is made to correspond to the inside diameter of the coil which is to be wound, and the center plate and templet are adjusted until one point in the circumference of the templet 1s directly under the central position of the needle of the sewing machine. The conductor is then fed, as indicated in Figs. 2 and 5 of the drawings, under the rollers 21 and 11 and is carefully sewed to the disk as shown in Fig. 5. As soon as the first turn of the coil is completed, the second turn is sewed to the first and the ordinary feed mechanism of the sewing machine serves to rotate the disk and the turns already complet :d, and to automatically wind the spiral. As the sewing process is continued, the center of the coil must necessarily move away from the needle, since the radius of the coil is constantly increasing and, since the coil is resting on the table, this adjustment is provided by the rod 6, the weights 32 and 33 tending to keep the coil from being forced away too rapidly. When the-coil iscompleted, it is ripped away from the disk 37 and the disk may be used-in making other coils.

It has been found, in practice, that rela-.

tively fine cotton thread may be employed for sewing cotton-covered conductors of small ga e and, if the firstturn of the coil is carefu 1y sewed tothe tem let, there is no danger of breaking the nee le of the machine by striking the center of the conductor.

I do not wish to be limited to the mechanism illustrated, since the same result may presumbly be secured by means of modified structures.

I. claim as my invention:

1. A coil for electrical apparatus comprising a series of convolutions of fiber-covered round wire disposed in a single plane, the

successive convolutions of the fiber covering being sewed to each other by zigza stitches, constituting a series of convolutions.

2. A coil for electrical apparatus comprising a flat spiral of fiber-covered small round wire, the successive turns of the fiber covering being sewed to each other by stitches constitutlng a spiral.

3. A coil comprising a spiral of small cotton-covered wire, the successive turns of the covering being sewed to each other by zigzag stitches constituting a spiral.

4. The method of constructing a coil for electrical apparatus that consists in sewing the first turn to a templet and each succeeding turn to the turn next preceding it.

5. The method of forming coils for electrical apparatus which consists in sewing one turn to a disk or templet and sewing each successive turn to the turn preceding by zigza stitches.

6. he method of constructing a coil for electrical apparatus which consists in sewing one turn to a disk or templet, gradually rotating the disk, stitching each succeeding turn to the preceding turn and adjusting the center of the coil, according to its increase in diameter, to maintain the stitching point stationary.

In testimony whereof, I have hereunto subscribed my name this sixth day of January,

Correction in Letters Patent No. 1,082,563;

It is hereby certified that in Letters Patent No. 1,082,563, granted December 30,

i 1913, upon the application of Harold B. Smith, of Worcester, Massachusetts, for an improvement in Coils for Electrical Apparatus, an error appears in the printed specification requiring correction as follows: Page 2, line 35, for the words to secure read secured to; and that the said Letters Patent should be read with this correction therein that the same may conform to the record ofthe case in'the Patent Oflice. a

Signed and sealed this 3rd day of February, A. D., 1914.

J. T. NEWTON,

Acting Oommz'ssz'oner of Patents.

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